usr.sbin/ppp/sig.c

   1 /*-
   2  * Copyright (c) 1997 - 1999, 2001 Brian Somers <brian@Awfulhak.org>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD$
  27  */
  28
  29 #include <sys/types.h>
  30
  31 #include <signal.h>
  32
  33 #include "log.h"
  34 #include "sig.h"
  35
  36 static int caused[NSIG];        /* An array of pending signals */
  37 static int necessary;           /* Anything set ? */
  38 static sig_type handler[NSIG];  /* all start at SIG_DFL */
  39
  40
  41 /*
  42  * Record a signal in the "caused" array
  43  *
  44  * This function is the only thing actually called in signal context.  It
  45  * records that a signal has been caused and that sig_Handle() should be
  46  * called (in non-signal context) as soon as possible to process that
  47  * signal.
  48  */
  49 static void
  50 signal_recorder(int sig)
  51 {
  52   caused[sig - 1]++;
  53   necessary = 1;
  54 }
  55
  56
  57 /*
  58  * Set up signal_recorder to handle the given sig and record ``fn'' as
  59  * the function to ultimately call in sig_Handle().  ``fn'' will not be
  60  * called in signal context (as sig_Handle() is not called in signal
  61  * context).
  62  */
  63 sig_type
  64 sig_signal(int sig, sig_type fn)
  65 {
  66   sig_type Result;
  67
  68   if (sig <= 0 || sig > NSIG) {
  69     /* Oops - we must be a bit out of date (too many sigs ?) */
  70     log_Printf(LogALERT, "Eeek! %s:%d: I must be out of date!\n",
  71               __FILE__, __LINE__);
  72     return signal(sig, fn);
  73   }
  74   Result = handler[sig - 1];
  75   if (fn == SIG_DFL || fn == SIG_IGN) {
  76     signal(sig, fn);
  77     handler[sig - 1] = (sig_type) 0;
  78   } else {
  79     handler[sig - 1] = fn;
  80     signal(sig, signal_recorder);
  81   }
  82   caused[sig - 1] = 0;
  83   return Result;
  84 }
  85
  86
  87 /*
  88  * Call the handlers for any pending signals
  89  *
  90  * This function is called from a non-signal context - in fact, it's
  91  * called every time select() in DoLoop() returns - just in case
  92  * select() returned due to a signal being recorded by signal_recorder().
  93  */
  94 int
  95 sig_Handle()
  96 {
  97   int sig;
  98   int got;
  99   int result;
 100
 101   result = 0;
 102   if (necessary) {
 103     /* We've *probably* got something in `caused' set */
 104     necessary = 0;
 105     /* `necessary' might go back to 1 while we're in here.... */
 106     do {
 107       got = 0;
 108       for (sig = 0; sig < NSIG; sig++)
 109         if (caused[sig]) {
 110           caused[sig]--;
 111           got++;
 112           result++;
 113           (*handler[sig])(sig + 1);
 114         }
 115     } while (got);
 116   }
 117
 118   return result;
 119 }